Change Filters Frequently to Optimize Furnace Efficiency

Change a Furnace Filter - Fiberglass Replacement

Photo: Greenwood Heating

Dust bunnies are multiplying, dog hair is piling up, and bird feathers are flying—oh my, it must be the furnace filter!

To change a furnace filter is perhaps the quickest and easiest way to maximize the efficiency of your heating system—and to help purify your home’s air.

Basic furnace filters are designed to trap dust, dirt, and airborne particulates before they can get into the system and potentially damage the fan or the heating coil. More expensive filters perform the same role, plus they can enhance the air quality in your home by trapping bacteria, pollen, and mildew and mold spores. Since most of the air in your house circulates through your HVAC system, furnace filters are your first line of defense against dust and airborne allergens.

Change a Furnace Filter - Comparison

Photo: Spaco

So how do you know when it’s time to change a furnace filter? Here are some general guidelines—although, as always, it is a good idea to check your owner’s manual for the manufacturer’s maintenance recommendations.

Typically you should change a basic, fiberglass or paper furnace filter every one to two months. And you should change or clean an electrostatic or HEPA filter every two to four months if…

- you have one or more furry pets
- you notice excessive to moderate dust buildup in your house
- one or more people in your home smoke
- your heating system fan runs most of the time
- you open your doors and windows frequently
- if you notice dust or dirt buildup on your current filter

Change a Furnace Filter - Fiberglass Disposable

Precisionaire EZ Flow Spun Fiberglass Filter

There are numerous options available in furnace filtration. The most basic model is an inexpensive fiberglass filter within a cardboard frame; these are typically one or two inches thick and come in a variety of sizes. The fiberglass interior traps larger particles of dust and dirt. These filters are disposable and designed to be thrown away after one to two months.

A step up from the basic filter is a disposable pleated paper filter, which will remove smaller particles of dust, dirt, and pollen. These filters are more expensive but will last from four months to one year.

The most expensive filters are reusable electrostatic filters, which are designed to trap smoke and smaller airborne particles. Able to be rinsed clean with a garden hose as needed, these filters can be reused for several years if properly maintained.

Some filters—in both disposable and reusable varieties—are rated as “antimicrobial” or “high efficiency particulate air” (HEPA) and are specially treated to trap microorganisms, including bacteria, mildew, fungus, mold, yeast and algae. If someone in your family has allergies, it may be worth investing in this filter type.

Actually changing the filter is a fairly easy task. Again, consult your manual for proper procedure, but typically the process is as follows: turn off the furnace; locate the service panel and remove; slide out the existing filter (located near the intake/outtake blower fan); slide in a new filter and turn the furnace back on.

For more on home heating, consider:

Gas Fireplaces 101
MERV Ratings: What Do They Mean?
11 Ways to Winterize Your Home on a Budget